Mechanical stoker



April 19 1927.

w. M. DUNCAN MECHANICAL STOKER F'ile'd Aug. 8. 1924 2 Sheets-Sheet 1 w mvm Aprii" l9 1927.

1,625,079 W. M. DUNCAN MEcHANIcAp sToKsR FiledAuz. 8. 1924 2 Sheets-Sheet 2 A 7' TOE/YE v3 Patented Apr. 19, 1927.

WILLIAM M. DUNCAN, OF ALTON, ILLINOIS.

MECHANICAL STOKER.

Application filed August 8, 1924. Serial No 730,873.,

This invention relates to improvements in mechanical stokers, and more particularly to means for transmitting draft to the fuelsupporting portion of an endless chain grate.

Prior to the present invention, a grate-of this kind'has been provided with draft boxes arranged transversely of the grate and a large wind box, or manifold. located entirely outside of the grate and built into the i irnace wall to supply draft to the several draft boxes.

One of my objects is to simplify the structure and reduce the cost of installation by locating the draft manifold within the endless traveling'grate. Another object is to produce a structure of this kind with independentl'y adjustable draft regulators controlling the flow of draft from the manifold to the respective draft boxes. A; further object is-to preventleakage of draft from the manifoldand draft boxes and to conveniently discharge the ashes and other fine material therefrom.

"Withthe foregoing and other objects in view, the invention comprises the novel constructiom combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodiment of the invention. However, it is to be understood that the invention comprehends changes, variations and modifications which come within the scope oftheclaims hereunto appended.

Fig. I is a longitudinal section illustrating stoker-embodying thefeatures a mechanical of this invention.

Fig. 11 is a transverse section of the structure shown in Fig. I.

Fig. III: isa section taken approximately on; the line Illnd in Fig. I1.

Fig. IV is an enlarged section showin' portions of the draft-regulating means.

A designates anendless traveling chain 4 grate arranged betweenthe sidewalls 1 of a furnace and supported partly by 'bars- 2 located immediately below the fuel-supporting portion of'the grate and partly by bars 3 011' which the lower portion ofthe grate travels. Additional supports are formed by a roll lat the rear of the-grate-and a-suitable number, of sprocket wheels 5' secured to an operating shaft 6 at the front of the grate. The shafts 6 may be driven in any suitable manner to cause the upper portion of'the grate to-travel inthe direction indicated by sealing arrows in Fig. I. The fuel is supplied through a hopper-7 at the front of the grate and the ashes are discharged by gravity at the rear of the grate.

Side frames 8, located at opposite sides of the grate, are provided with bars9- (Fig. 1-1 at their top faces to prevent leakageof draft around the sides of the grate. Beams 10*arranged transversely of the grate are con.- nected by, means of angle plates 11 to the side frames 8. The spacebetween the upper and lower portions of the grate is divided by'means of transverse partitionsl-Q and 12" extending, downwardly from beams '10 to form a series of draft boxeswhich lie'transversely of the grate. The lower margin of each partition is provided with a recess 18 (Fig; I) open at the bottom to receivea loose bar 14. The bottoms ofjthe draft boxes are formed by independent-1y yieldable plates 15 arrangedlongitudinally of the grate andresting upon the traveling lower portion of'saidgrate. Each of these loosely, mounted plates is turned upwardly at its rearend m form an abutment 16 (Fig. I) which engagesa tube 17 to prevent longitudinal displacement of said plates- Excessive friction between the grate and the upturned abutment- I6 is prevented by a roll 17 shown in Fig. I. To prevent leakage of draft between the lowermarginsof the partitions 12 and the yielding bottom plates 15, the loose sealing bars'la rest upon the plates-15' and ashes arepermitted to accumulate at these sealing bars, as'suggested in Fig. I.

To illustrate oneform of the invention, 1 have shown a pair of draft manifolds B'ljocated within the grate and surrounded by the side margins thereof; The outer side walls of the manifolds are formed by the side frames 8.. 18 designates: the inner side walls and 19- the top walls. To prevent leakage of draft between the bottoinf plates 1-5 and" the side walls 18, said walls are provided at their lower edges with recesses 20 (Fig. 11), and sealing bars 2f which rest upon plates 15- are loosely mounted in these recesses. Ashes are permitted toaccumulate at opposite sides of bars 21, as shown in Fig. II, so as to produce ash-seals at these points. The bottoms of the draft manifolds are formed by the yi'eld'able plates 15 at the side margins of the grate, and additional seals are produced by arranging ang-l'e bars 22 at thelower outer corners of the manifolds, as shown in Fig. II, these angle bars being loosely secured by Z-bars 23 secured to the side frames 8.

Openings 24 are formed in the yieldable plates to permit free discharge of ashes and other fine material dropping from the top of the grate. To prevent leakage of draft through these openings 24, bodies of ashes 25 are preferably maintained below the grate, as shown in Fig. II. The ashes passing through the openings 24 enter the traveling lower portion of the grate and are carried forwardly therein until the grate links separate in passing to the sprocket wheels 5 atthe left side of Fig. I. At this point the ashes and other line material drop from the grate.

The manifold B at the right side of Fig. II is supplied with a forced draft passing from a conductor 26 leading to an inlet opening 27 formed in the outer side wall of said manifold. The draft manifold B at the left side of Fig. TI is supplied through a conductor 26 leading to the inlet 27. The in ner side wall of each manifold is provided with openings 28 through which the draft is transmitted to the respective draft boxes, and the top wall of each manifold is provided with an opening 29 for the discharge of draft to the draft boxes.

The series of draft boxes form different draft zones and the structure includes independently adjustable draft regulators controlling the flow of draft to the respective zones. Closures 30 and 30 are hinged at 31 (Fig. II) to control the flow of draft through the openings 29, and closures 32 and 32 are adapted to control the flow through the openings 28. An suitable means may be employed to at just these closures, but the closures for each transverse draft zone should be adjustable independently of the closures in the other zones, although the set of closures in a single zone may be operated simultaneously. The closure 32 at the right side of Fig. II is fixed to a tube 33 slidable in a bridge 34: and also adapted to slide in a sleeve 35 secured to the conductor 26. This tube 33 extends to the exterior of conductor 26 where it has an operating handle 36. Obviously, the tube 33 can be reciprocated to adjust the closure 32. The hinged closure 30 above the tube 33 is opened by gravity and controlled by a finger 37 fixed to the tube and engaging the inclined bottom face of said closure 30.

The closures 32 at the left of Fig. II is carried by a rod 38 slidable in one of the bridges 34 and extending entirely through the tube 33. This rod 38 carries a finger 39 to actuate the hinged closure 30', and it is moved longitudinally to actuate the closures 30 and 32. The outer end of the rod 38 is provided with an operating handle 36. To prevent rotary displacement of the operating fingers 37 and 39 and the closures 32 and 32, the tube 33 may be splined to the sleeve 35, asshown at 40 in Fig. IV, and the rod 38 may be 'splined at ll'to said tube.

Each transverse draft zone is equipped with a set'of the closures shown by Fig. II, so the delivery of draft from the manifolds to the respective draft boxes can be regulated to produce the desired draft in each zone. The upper portions of the transverse draft boxes extend entirely across the grate, as seen in Fig. 11, and although the middle of each draft box may extend from the upper to the lower portion of the grate, the ends of the draft boxes are comparatively shallow to provide the spaces for the draft manifolds B which lie between the ends of the draft boxes and the lower portion of the grate.

I claim:

1. A mechanical stoker comprising anendless chain grate, draft boxes surrounded by the grate and arranged transversely thereof to form a series of draft zones in the grate, said draft boxes being open at the top for the discharge of draft through the upper portion of the grate, a draft manifold surrounded by said grate and located below portions of said draft zones so as to lie within the grate and between said portions of said draft zones and the lower portion of the grate, the top wall of said draft manifold having discharge openings for the discharge of draft to said draft boxes, and means for regulating the flow of draft through said discharge openings.

2. A mechanical stoker comprising an endless chain grate, draft boxes surrounded by the grate and arranged transversely thereof to form a series of draft zones in the grate, said draft boxes being open at the top for the discharge of draft through the upper portion of the grate, a draft manifold surrounded by said grate and located below portions of said draft zones so as to lie within the grate and between said portions of said draft Zones and the lower portion of the grate, the top wall of said draft manifold having discharge openin s for the dis charge of draft to said draft boxes, the bo tom wall of. said draft manifold having an ash outlet directly above the lower portion of the grate, and means for regulating the flow of draft through said discharge openmgs.

3. A mechanical stoker comprising an endless chain grate, draft boxes surrounded by the grate and arranged transversely thereof to form aseries of draft zones in the grate, said draft boxes being open at the top for the discharge of draft through the upper portion of the grate, a draft manifold surrounded by said grate and located below portions of said draft zones so as to lie within the grate and between said portions of said draft zones and the lower portion of the grate, the top wall of said draft manifold having discharge openings for the discharge of draft to said draft boxes, the bottom Wall of said draft manifold being in contact with and supported by-the lower portion of the grate and said bottom wall being provided with an ash outlet for the discharge of ashes into said lower portion of the grate.

4. A mechanical Stoker comprising an endless chain grate, draft boxes surrounded by said grate, said draft boxes being arranged transversely of the grate and being open at the top for the discharge of draft through the upper portion of said grate, said draft boxes having bottom walls supported by the lower portion of the grate and having openings for the discharge of ashes into the grate, a draft manifold surrounded by said grate and extending lengthwise thereof, said draft manifold havlng an inlet for the draft and discharge openings communicating with the respective draft boxes, and independent- 1y adjustable draft regulators controlling the flow of draft through the respective discharge openings.

5. A mechanical stoker comprising an endless chain grate, draft boxes surrounde by the grate and arranged transversely thereof to form a series of draft zones in the grate, said draft boxes being open at the top for the discharge of draft through the upper portion of the grate, a draft manifold surrounded by said grate and located below portions of said draft zones so as to lie within the grate, said draft boxes and manifold being provided with bottom walls resting upon the lower portion of said grate and having openings for the discharge of ashes into the grate, the manifold being in communication with the respective draft boxes and provided with an inlet for the admission of draft.

In testimony that I claim the foregoing I hereunto affix my signature.

WILLIAM M. DUNCAN. 

